1. Field of Invention
This invention relates to steerable catheters. More particularly, this invention relates to an improved control handle for a steerable catheter which precisely and consistently controls the deflection of the tip of the catheter.
2. Prior Art
Catheters of various types have been utilized for medical procedures for many years. For example, they have been used to convey an electric stimulus to a selected location within the human body or to monitor or make measurements for diagnostic purposes of activities within the human body. Such catheters examine, diagnose and treat areas which are otherwise unaccessible without invasive procedures. In use, the catheter is first inserted into a major vein or artery or other body lumen which is near the body surface. The catheter is then guided to the area for examination, diagnosis or treatment by manipulating the catheter through the body lumen. As the utilization of catheters in remote and difficult to reach locations within the body has increased, it has become more important to control precisely the movement of the tip of the catheter within the body lumen.
Control of the movement of catheters is difficult because of their construction. The body of conventional catheters is long and tubular. To provide sufficient control over the movement of the catheter, it is necessary that these tubular catheters be made somewhat rigid. However, catheters must be flexible enough to navigate through the body lumen to arrive at the desired location within the body where the medical procedures will be performed without harming the body lumen.
One of the early methods used to control the movement of catheters within a body was by the use of preshaped catheter tips. This construction had advantages for certain limited medical procedures but because the configuration of the bend could not be changed after insertion and because of the difficulty in orienting the bend in the desired direction as a result of the torsional flexibility of the catheter, new improved catheters were necessary.
Short and rigid controllable tip devices have also been used for special procedures where the degree of bending of the tip could be controlled from the handle. However, these devices are not satisfactory for vascular purposes where the catheter must be long, slender and flexible throughout its entire length.
To increase the ability to move and navigate within a body, longer, flexible catheters containing steerable, deflectable tips have been designed. Because the deflectable tips of these flexible catheters are bendable, they can be used for a number of medical procedures which require precise control over the orientation of the catheter tip. With these devices the deflection of the steerable tip is achieved by increasing or decreasing the axial compressive force on one side of the steerable tip by applying tension to the pull wire. By increasing the compressive force to one side of the tip, it is deflected in a predetermined direction.
To control precisely the movement of these steerable catheters, control handles have been attached at the proximal end of the catheter body. For example, U.S. Pat. No. 4,586,923 describes certain devices useful for controlling the movement of steerable catheters.
Various other types of control handles have been designed to control the movement of steerable catheters. For example, U.S. Pat. No. 5,195,968 discloses a design for a catheter steering mechanism which is designed to bend the tip of a catheter. See also U.S. Pat. No. 5,254,088, a related application. U.S. Pat. No. 5,185,004 also discloses a steerable catheter handle for use with a steerable catheter system.
Another control handle which can be rotated while in use is disclosed in U.S. Pat. No. 4,960,134. This patent discloses a rotatable catheter handle which uses a piston contained within the control handle to create and maintain pressure on the pull wire. As the piston is extended from the control handle, the catheter tip is bent. See also, U.S. Pat. Nos. 5,125,896, 4,874,371 and 5,002,560.
Other medical procedures also use medical instruments containing guidewires with bendable tips and control handles. See for example, U.S. Pat. Nos. 5,035,696, 4,799,496, and 3,521,620. While each of these devices uses a handle to control the deflection of the tip, precise one-handed control of the movement and deflection of the catheter tip is still a problem. In addition, precise control of the movement of the catheter tip even when the handle is being rotated must still be maintained.
Medical procedures utilizing these steerable catheters frequently require an extended period of time to complete by even skilled medical practitioners. Such procedures lasting many hours create problems of control of the catheter tip even with existing steerable catheter handles. Further, as most of these procedures are done with only a single hand of the physician controlling the movement of the catheter, it is important to provide a mechanism to limit the movement of the tip while maintaining the tip in an existing bent position. Thus, a new handle which precisely controls the movement of the catheter tip and which is easy to use is still needed.
Accordingly, it is an object of this invention to disclose a steerable catheter with an improved control handle.
Another object of this invention is to disclose a steerable catheter with an adjustable control handle which has precise control of the deflection of the tip of the catheter.
Another object of this invention is to disclose a steerable catheter with control handle wherein the control handle can be operated by use of only one hand of the medical practitioner.
Another object of this invention is to disclose a steerable catheter which operates in the same manner regardless of its rotational orientation.
It is a still further object of this invention to disclose a steerable catheter with a control handle wherein the deflection of the tip can be maintained in a set position during use.
These and other objects are obtained by the design of the control handle of the steerable catheter of the instant invention.